List of Excipients in Branded Drug PENLAC

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Bausch Health US LLC	PENLAC	ciclopirox	0187-5180	BUTYL ESTER OF METHYL VINYL ETHER/MALEIC ANHYDRIDE COPOLYMER
Bausch Health US LLC	PENLAC	ciclopirox	0187-5180	ETHYL ACETATE
Bausch Health US LLC	PENLAC	ciclopirox	0187-5180	ISOPROPYL ALCOHOL

PENLAC Excipient Strategy and Commercial Opportunities in Ciclopirox Nail Lacquer

Last updated: September 9, 2026

PENLAC is a ciclopirox 8% topical nail lacquer for mild-to-moderate toenail and fingernail onychomycosis. Its commercial value is tied less to the active ingredient, which is genericized, than to film formation, nail penetration, drying time, cosmetic acceptability, removal burden, packaging, and manufacturing control. The core formulation uses hydroxypropyl chitosan with volatile solvents, creating opportunities for improved generic products, lower-cost manufacturing, faster-drying systems, water-compatible lacquers, and combination products.

What is PENLAC and what excipients does it contain?

PENLAC Nail Lacquer is a prescription topical solution containing 8% ciclopirox. The FDA-approved regimen requires daily application for up to 48 weeks, with weekly removal of the accumulated lacquer using alcohol or another suitable solvent. The product is intended for onychomycosis involving limited portions of the nail and without lunula involvement. [1]

The labeled inactive ingredients are:

Component	Functional role
Hydroxypropyl chitosan	Film former, adhesion promoter, nail-surface interaction
Ethyl acetate	Volatile solvent and drying-rate modifier
Isopropyl alcohol	Solvent, co-solvent, antimicrobial manufacturing aid and evaporation modifier

The formulation is designed to form a thin film on the nail plate. The film must remain sufficiently cohesive to retain ciclopirox while allowing drug diffusion into the nail. Excessively strong adhesion can increase removal difficulty; insufficient adhesion can reduce residence time and dose delivery.

Why hydroxypropyl chitosan matters

Hydroxypropyl chitosan is the central excipient in the PENLAC platform. Chitosan derivatives can provide:

• Film formation after solvent evaporation
• Adhesion to keratinized surfaces
• Potential interaction with the negatively charged nail surface
• Improved local retention
• Compatibility with polar and partially aqueous formulation systems

The excipient is commercially relevant because substitution level, molecular weight, viscosity, residual solvent, moisture content, particle size, and microbial quality can affect product performance. A nominally equivalent excipient from a different supplier may not produce equivalent lacquer behavior.

How does the PENLAC formulation work?

PENLAC applies ciclopirox in a volatile solvent system. After application, ethyl acetate and isopropyl alcohol evaporate, leaving a polymeric film containing ciclopirox on the nail.

The product must balance five performance variables:

1. Wetting of the nail surface
2. Drying time
3. Film uniformity
4. Adhesion and flex resistance
5. Drug release and nail penetration

A formulation that dries too quickly may produce poor spreading and dose nonuniformity. A system that dries too slowly can reduce patient adherence and increase transfer to footwear or bedding. A film that is too brittle can crack; a film that is too flexible or soft can smear and retain debris.

The commercial problem is substantial. Daily application for 48 weeks creates a high adherence burden, while weekly lacquer removal adds a separate compliance step. A product that reduces removal frequency or improves drying can compete even if it contains the same active ingredient and concentration.

What excipient strategies are available for generic and improved PENLAC products?

1. Preserve the hydroxypropyl chitosan platform

The lowest-risk strategy is to retain hydroxypropyl chitosan and optimize the solvent ratio, polymer grade, and manufacturing process.

Potential advantages include:

• Lower development risk
• Greater similarity to the reference product
• Familiar regulatory pathway for an ANDA or comparable generic route
• Established product-use behavior
• Less need to establish a new clinical benefit-risk profile

The principal risks are supply concentration, grade-to-grade variability, and difficulty demonstrating equivalent in vitro performance. The manufacturer must control polymer specifications rather than relying only on chemical identity.

2. Optimize the solvent system

Ethyl acetate and isopropyl alcohol provide rapid evaporation, but the ratio determines viscosity, drying time, wetting, and film morphology.

Potential solvent changes include:

• Ethanol substitution or partial substitution
• Ethyl acetate reduction to improve worker safety or odor
• Use of isopropyl acetate or other volatile esters
• Addition of small quantities of slower evaporating co-solvents
• Solvent systems that reduce crystallization during drying

A faster-drying product could command a premium in specialty pharmacies and dermatology channels. The regulatory risk is that solvent changes can alter ciclopirox activity, crystallinity, release, and nail penetration.

3. Use alternative film-forming polymers

Potential replacement or co-polymer systems include:

• Acrylate copolymers
• Cellulose derivatives
• Polyvinylpyrrolidone derivatives
• Methacrylate copolymers
• Povidone-based systems
• Other chitosan derivatives

The commercial objective is not simply to create a stronger film. It is to improve the relationship between adhesion, permeability, removability, and cosmetic appearance.

Alternative polymers may support claims such as:

• Faster drying
• Reduced flaking
• Lower odor
• Improved gloss
• Reduced weekly removal burden
• Better compatibility with cosmetic nail products

These changes can create a differentiated 505(b)(2) product, but they may not fit the simplest ANDA strategy if the formulation differs materially from the reference product.

4. Develop water-compatible or low-VOC systems

A water-compatible lacquer could reduce odor and solvent exposure. The main technical challenge is that ciclopirox has limited water solubility, and the film must remain coherent after water evaporation.

Possible approaches include:

• Solubilizing agents
• Cyclodextrin complexes
• Hydroalcoholic systems
• Nano- or microdispersions
• Water-dispersible polymer films
• Combination solvent systems

Water-based systems may improve patient acceptability but can produce slower drying, lower drug loading, tackiness, and microbiological preservation challenges. They may also require a more extensive clinical or comparative performance package.

What commercial opportunities exist for PENLAC-compatible excipients?

The most attractive opportunities are formulation-driven rather than active-ingredient driven.

Opportunity	Commercial proposition	Main development barrier
Fast-drying lacquer	Shorter wait time after application	Maintaining uniform film and drug delivery
Reduced-removal lacquer	Less weekly maintenance	Demonstrating retained efficacy and film control
Low-odor formulation	Better patient acceptance	Solvent replacement can alter release
Water-compatible lacquer	Lower VOC and cosmetic appeal	Ciclopirox solubility and preservation
Brush-free applicator	Better dose consistency and hygiene	Device compatibility and user testing
Unit-dose packaging	Lower contamination risk	Packaging cost and waste
Combination antifungal lacquer	Broader or faster activity	Clinical evidence and intellectual property
Pediatric-friendly product	Improved usability	Safety, acceptability, and dosing data
Combination nail-care product	Moisturizing or keratolytic support	Drug-cosmetic regulatory boundary

Excipient supplier opportunity

A supplier can pursue a differentiated hydroxypropyl chitosan platform by offering:

• Narrow molecular-weight distribution
• Defined degree of substitution
• Controlled viscosity
• Low bioburden and endotoxin specifications
• Consistent residual solvent profile
• Pharmaceutical-grade documentation
• Stability data in ciclopirox systems
• Multiple grades for fast- and slow-drying films

The supplier’s strongest commercial position would come from a formulation package rather than a raw-material sale. That package could include prototype compositions, rheology data, film testing, drug-release studies, nail permeation data, and regulatory support.

What FDA regulatory pathways apply to PENLAC products?

ANDA pathway for generic ciclopirox lacquer

An ANDA is the principal pathway for a product that matches the reference drug in active ingredient, dosage form, strength, route, and relevant performance characteristics. FDA-approved generic ciclopirox 8% topical solutions demonstrate that the active ingredient and product category are commercially open to generic competition. [2]

For a lacquer, the critical equivalence package may include:

• Assay and impurities
• Viscosity
• Drying time
• Film thickness
• Adhesion
• Appearance
• Drug-release testing
• Drug crystallinity
• In vitro permeation or nail penetration
• Microbial limits
• Container-closure performance
• Stability under temperature and humidity stress

The more the formulation departs from the reference product, the greater the risk that the product cannot rely on simple qualitative and quantitative sameness.

505(b)(2) pathway for differentiated formulations

A 505(b)(2) application may be appropriate for:

• A new polymer system
• A different solvent platform
• A different application schedule
• A new delivery device
• A new combination product
• Modified removal requirements
• A new indication or patient population

The 505(b)(2) route can support commercial differentiation, but it typically requires a larger clinical and regulatory investment than a conventional generic program.

OTC opportunity

An OTC switch would require FDA review of safety, efficacy, labeling, and consumer usability. PENLAC’s long treatment period, prescription history, diagnosis-dependent use, and need to distinguish fungal nail disease from nonfungal nail disorders make an immediate OTC strategy difficult. An OTC opportunity would likely require a new product concept, not simply relabeling the existing prescription lacquer.

What is the patent and exclusivity position of PENLAC?

PENLAC’s commercial exclusivity is no longer the primary barrier to entry. Ciclopirox is an established generic antifungal, and FDA-approved generic 8% topical solutions have entered the U.S. market. [2]

The relevant protection categories are:

Protection category	Position for PENLAC-type products
Active-ingredient patents	Historical protection has expired or is no longer commercially decisive
Original formulation patents	Any historical rights require confirmation in the current Orange Book and USPTO records
Method-of-use patents	Potentially relevant only if claims cover a distinct dosing schedule or patient group
Device patents	Potentially relevant for applicators, brushes, or metered delivery
New formulation patents	Available for genuinely differentiated polymers, solvents, or release systems
Trade secrets	Important for polymer processing, filling, drying, and quality-control methods
Regulatory exclusivity	Not a meaningful current barrier for the established generic product

The central intellectual-property opportunity is a new formulation or delivery system. A patent directed only to the use of ciclopirox in a conventional lacquer is likely to face significant validity and obviousness pressure. Stronger claims would focus on measurable technical features, such as defined polymer substitution, drying characteristics, nail penetration, controlled release, or reduced removal frequency.

What Orange Book issues matter?

The FDA Orange Book identifies approved drug products and, where applicable, listed patents and exclusivity. The PENLAC reference listing and current generic approvals should be reviewed by product number and dosage form because topical solutions can have different regulatory treatment from creams, gels, or shampoos containing ciclopirox. [3]

A generic applicant should assess:

• Whether the reference product remains eligible as the reference listed drug
• Whether any listed patents remain active
• Whether Paragraph IV certification is required
• Whether a Section VIII statement can omit a method-of-use patent
• Whether formulation claims create a separate patent risk
• Whether device or packaging claims are listed or separately enforceable

Are Paragraph IV challenges relevant to PENLAC?

Paragraph IV litigation is less central for a mature ciclopirox lacquer than for a recently approved branded product. A generic applicant may still face litigation if a sponsor lists an unexpired formulation or method-of-use patent in the Orange Book.

The likely litigation issues would include:

• Patent listing eligibility
• Claim construction for polymer and solvent limitations
• Obviousness of substituting a known film former
• Written description and enablement for formulation ranges
• Anticipation by earlier antifungal lacquer references
• Equivalence of a generic’s formulation to the patented product
• Regulatory use of the patented method

A settlement agreement could delay launch, permit an authorized generic, or impose restrictions on formulation, labeling, or manufacturing. Public databases such as FDA’s Paragraph IV litigation records, PACER, and the Federal Register should be used to verify any current dispute. [3,4]

How does PENLAC compare with competing antifungal products?

Product or class	Active ingredient	Dosage form	Typical treatment burden	Commercial differentiation
PENLAC	Ciclopirox 8%	Daily nail lacquer	Daily use for up to 48 weeks; weekly removal	Established lacquer platform
JUBLIA	Efinaconazole 10%	Topical solution	Daily application; no lacquer removal in the same manner	Brush-on solution and broader nail access
KERYDIN	Tavaborole 5%	Topical solution	Daily application	Small-molecule nail penetration strategy
Amorolfine products	Amorolfine	Nail lacquer	Less frequent dosing in some markets	Longer dosing intervals outside the U.S.
Oral terbinafine	Terbinafine	Tablet	Shorter systemic course	Higher systemic exposure and monitoring concerns
OTC topical products	Various agents	Creams, liquids, sprays	Variable	Lower price but limited nail penetration

JUBLIA and KERYDIN established competitive pressure around easier application and nail penetration. [5,6] PENLAC’s excipient opportunity is to close the usability gap while retaining generic cost advantages.

What formulation patents could protect a next-generation PENLAC product?

A defensible patent estate would usually require more than a broad claim to ciclopirox in a nail lacquer.

Polymer and composition claims

Potential claim elements include:

• Hydroxypropyl chitosan within a defined substitution range
• A specified molecular-weight range
• A defined polymer-to-ciclopirox ratio
• A solvent ratio producing a target drying time
• A film with defined water uptake or mechanical strength
• A formulation that limits ciclopirox crystallization

Performance claims

Performance-based protection can target:

• Drying within a defined period
• Adhesion after repeated washing
• Drug release over a defined interval
• Nail plate penetration at a specified depth
• Reduced weekly removal frequency
• Improved retention after footwear exposure

These claims require robust analytical methods and reproducible test data. Generic patents based only on subjective cosmetic benefits are less durable.

Device and packaging claims

Commercially useful device patents may cover:

• Metered-dose applicators
• Brush geometries that reduce dose variability
• Sealed single-use applicators
• Solvent-resistant closure systems
• Packaging that limits evaporation
• Child-resistant containers
• Applicators designed for subungual delivery

Packaging improvements can produce a practical commercial advantage when the active product is otherwise commoditized.

What manufacturing and supply-chain barriers affect PENLAC opportunities?

The main manufacturing risks are solvent handling, polymer hydration, batch-to-batch viscosity variation, and evaporation during filling.

Critical controls include:

• Closed solvent-transfer systems
• Explosion-protected manufacturing areas
• Controlled mixing temperature
• Polymer dispersion and hydration time
• In-process viscosity
• Fill-weight accuracy
• Container closure integrity
• Headspace solvent loss
• Brush compatibility
• Stability under accelerated conditions

Hydroxypropyl chitosan can introduce supply-chain dependence if only a small number of suppliers meet pharmaceutical-grade requirements. A dual-sourcing strategy should qualify material by functional performance rather than identity alone.

The container closure is part of the product performance system. Ethyl acetate and isopropyl alcohol can alter elastomers, liners, adhesives, and brush components. Evaporation can increase viscosity and change dose delivery during the product’s in-use period.

What generic launch scenarios exist for PENLAC?

Low-cost conventional generic

This product uses the established ciclopirox 8% lacquer architecture and competes through pharmacy price, payer coverage, and supply reliability. It has the lowest development risk and the weakest product differentiation.

Premium generic

This product retains the reference active ingredient but improves brush design, drying time, odor, packaging, or in-use stability. It can command a higher price if the manufacturer obtains separate intellectual-property protection or secures favorable channel placement.

505(b)(2) next-generation lacquer

This product changes the excipient platform or dosing regimen and seeks a differentiated label. It has higher clinical and regulatory costs but can support a stronger commercial position.

Combination product

Potential combinations include ciclopirox with a keratolytic, nail-softening agent, or another antifungal. The technical rationale is improved access through the nail plate. Combination products face added safety, compatibility, clinical, and patent requirements.

What is the revenue exposure and market opportunity?

PENLAC itself is a mature product, so revenue exposure is concentrated in price, formulary position, and generic substitution rather than in loss of a protected monopoly. The commercial opportunity lies in the larger category of topical nail antifungals and in excipient-enabled product differentiation.

Revenue can be improved through:

• Lower cost of goods
• Improved refill persistence
• Reduced product waste
• Premium packaging
• Specialty pharmacy distribution
• Dermatology-focused promotion
• Licensing of a differentiated polymer platform
• Regional licensing in markets where nail lacquer use is established
• Co-development with generic manufacturers

The strongest economic case is a platform that can be applied to multiple topical nail products, not a single ciclopirox SKU. A validated lacquer technology could support products containing ciclopirox, amorolfine, terbinafine, efinaconazole, or other poorly penetrating actives, subject to compatibility and regulatory requirements.

How strong is the PENLAC patent estate?

The historical PENLAC exclusivity position is weak relative to a new branded drug because ciclopirox 8% topical solutions are already genericized. The stronger forward-looking strategy is to build protection around formulation performance, manufacturing controls, and delivery hardware.

Estate component	Relative strength
Ciclopirox composition claims	Low for new entrants because of maturity
Conventional nail lacquer claims	Low to moderate
Defined hydroxypropyl chitosan grades	Moderate if technically specific
Fast-drying or low-odor systems	Moderate if supported by unexpected performance
Reduced-removal formulations	Moderate to strong if clinically validated
Applicator and packaging claims	Moderate
Manufacturing-process claims	Moderate, with enforcement challenges
Trade secrets	Potentially strong but difficult to detect and enforce

Key Takeaways

• PENLAC is a ciclopirox 8% hydroxypropyl chitosan nail lacquer with ethyl acetate and isopropyl alcohol.
• The active ingredient is commercially mature; formulation and delivery technology provide the main differentiation opportunity.
• The most practical generic strategy is to preserve the reference formulation architecture while optimizing solvent ratio, polymer grade, drying time, and packaging.
• A 505(b)(2) strategy may support reduced-removal dosing, water-compatible systems, new applicators, or combination products.
• Hydroxypropyl chitosan quality is a key supply-chain and product-performance variable.
• The strongest patent opportunities concern measurable film, release, penetration, drying, removal, and device characteristics.
• PENLAC’s competitive weakness is treatment burden: daily use for up to 48 weeks and periodic lacquer removal.
• A commercially valuable excipient platform should be adaptable to multiple topical nail antifungals, not limited to ciclopirox.

FAQs

Can hydroxypropyl chitosan be replaced in a generic PENLAC product?

Yes, but replacing it can increase regulatory and equivalence risk. The alternative polymer must reproduce relevant film, adhesion, release, drying, and nail-penetration performance.

What excipient is most important in ciclopirox nail lacquer?

Hydroxypropyl chitosan is the most strategically important excipient because it controls film formation, adhesion, and local retention after solvent evaporation.

Can a faster-drying ciclopirox lacquer be patented?

Potentially. Protection is more defensible when the formulation has defined composition and demonstrates unexpected improvements in drying, drug delivery, adhesion, or patient use.

Is a water-based PENLAC formulation commercially feasible?

Potentially, but ciclopirox solubility, drying time, film integrity, microbial preservation, and nail penetration create material development challenges.

Does PENLAC have biosimilar competition?

No. PENLAC contains the small-molecule antifungal ciclopirox, so competing products are generics or follow-on formulations, not biosimilars.

References

1. U.S. Food and Drug Administration. (2020). PENLAC nail lacquer: Ciclopirox 8% topical solution prescribing information. FDA.
2. U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs database. FDA.
3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
4. U.S. Food and Drug Administration. (2024). Paragraph IV drug product applications: Patent certifications and litigation records. FDA.
5. U.S. Food and Drug Administration. (2020). JUBLIA: Efinaconazole topical solution prescribing information. FDA.
6. U.S. Food and Drug Administration. (2020). KERYDIN: Tavaborole topical solution prescribing information. FDA.